Katia_chan, why not send another e-mail to the DGS inquiring about your position on the waitlist, especially since you already have an acceptance? You could tell them that you wanted to follow up to let them know that you have received another offer but still remain very interested in their program. Perhaps, like you state above, they really do not know how many applicants they will be able to admit off of the waitlist, but you will never really know where you stand until you ask. Best wishes and congratulations!